Ex vivo model of using the method of optical skin clearing during antimicrobial photodynamic action

This study evaluated the efficacy of transcutaneous photodynamic therapy using blue (428 nm) LED irradiation on Staphylococcus aureus 11 in combination with a water-soluble cationic pyridyl porphyrin and optical clearing agents (OCA) in an ex vivo model. Results showed that OCA significantly enhanced photodynamic inactivation with a 61% reduction in bacterial cell counts after 15 minutes of light exposure, comparable to direct irradiation. Optical parameter analysis revealed a decrease in scattering and absorption coefficients and an increase in light penetration depth (up to 121,6%) in OCA-treated skin samples. The results confirm that optical clearing improves the efficacy of antimicrobial photodynamic action by enhancing light penetration into deeper tissue layers, reducing the need for high laser intensities, and minimizing superficial tissue damage. This approach holds promise for the treatment of skin, mucosal and soft tissue infections in humans and animals, offering valuable insights into light-tissue interactions and optimizing photodynamic therapy while reducing the risks associated with the use of LEDs and lasers.